Valve-lifting device



W. C. MERWARTH VALVE LIFTING DEVICE Dec. 31, 1929.

Filed Oct. 27, 1926 Patented nee. at, was

UNITED "STATES PATENT! OFFICE WILLIAM C. HERWARTH, OF EAS'ION,PENNSYLVANIA, ASSIGNOR 1'0 PMNBYIIVANIA. rm 6'5 COMPRESSOR COMPANY, OFEASTON, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA VALVE-LIFTING DEVICEApplication filed October 27, 1926. Serial No. 144,465.

This invention relates to valve lifting devices and particularly to afluid pressure actuated means for lifting and holding a compressor valvefrom its seat to unload the compressor. v

An object of the invention is to provide an improved form of valvelifter for compressors adapted, when the valve is in its raised orunloading position, to provide a pressure ti ht enclosure whereby fullreceiver pressure will be supplied to the unloading device and leakageof fluid will be prevented.

Another object of the invention is to provide a piston loosely movablewithin an unloading cylinder to which fluid under pressure is adapted tobe admitted, the piston in moving being adapted to carry with it asecond piston member having fingers extending to and engaging the valveplate.

Another object of the invention is to provide a cylinder for a pistonmovable to operate compressor unloading devices which has a seat at oneend of the cylinder adapted to contact with a surface on the piston whenthe piston is in its valve unloading position.

Another object of the invention is to provide a pressure tight seatbetween one end of the cylinder and a second piston member moved by apiston operating within the cylinder so that during normal operation ofthe com ressor fluid will be prevented from leaking rom the compressorintake passages out through the unloading devices.

With these and other objects in View my invention consists in thefeatures of construction and operation set forth in the followingspecification and illustrated in the accompanyin drawings.

In t e accompanying drawing annexed hereto and forming a part of thisspecification, I have shown my invention embodied in a compressorunloading device operated by lifting and holding an inlet valve in an inoperative or open position but it will be un derstood that the inventioncan be otherwise embodied and that the drawing is not to be construed asdefining or limiting the scope of the invetnion, the claims appended tothis specification being relied upon for that purpose.

The figure of the drawing shows acentral vention' comprises thefollowing principal parts:' First, a valve movable between open andclosed positions during normal operation of'the compressor; second, apiston member having fingers adapted to contact with and lift the valvefrom its seat; third, another piston member movable within a cylinderand adapted to force the piston member carrying the fingers in adirection to lift the valve, these two piston members forming a two-partpiston; fourth, a seat formed on said cylinder adapted to be in contactwith a surface of one of the pistons when the piston has been moved to aosition to lift the valve; fifth, a cover plate or one end of thecylinder secured in pressure tight relation'to the cylinder; sixth,closely co-acting surfaces between the supporting member for the valveand the piston member carrying the valve engaging fingers adapted to bein contact when the valve lifting member is in its retracted position;seventh, means to admit fluid under pressure to the space within thecylinder to actuate the piston members and carrying the valve liftinfingers, and resilient means normally forcing the piston members andcarrying the fingers toward their retracted position. I

Referring more in detail to the figure of the drawing, I provide a valveassembly having a valve seat 10, a cover plate 11 and a valve plate 12mounted in a suitable opening formed in the cylinder wall 13 of acompressor. The valve shown is of the inlet type adapted to admit fluidbeing compressed from inlet passages 14 to the space within the cyl- Iinder 15. It will be understood that the compressor. may be simple orcompound and the intake passages 14 may admit fluid to the low or a highpressure cylinder.

To support the valve assembly 10-11 and 12 in operative position in thecompressor wall 13, a yoke supporting member 16 is provided having a rimportion 17 adapted to contact with the valve seat 10.- The. lowerportion of this yoke member 16 is formed as a cylinder 18 open at thelowermost end and having a cover plate 19 at this end to close 1t.

To temporarily retain the cover plate 19 in position on the cylinder 18during assembling a resilient retainer 20 may be used. To secure theabove parts in their operative position a cover 21 is secured to thecompressor wall 13 by means of screws one of which'is shown at 22. Ascrew 23 of large size is threaded through this cover 21 and engages thelower end of the cover plate 19 for the cylinder 18.

Adapted to operate within the cylinder 18 is a piston 24 which maybevery loosely fitted so that it will slide freely.

- piston 24 is the cylindrical end portion of a second piston member 25to which fingers 26 are attached at its upper end. In the lower positionof the piston member 25 the fingers 26 are not in contact with the valveplate 12. Movement upward of this piston member 25 and the fingers 26 bythe piston 24 forces the fingers 26 against the valve plate 12 to raiseand hold the valve plate 12 1n its open position.

In order to raise the piston 24 and the piston member 25, fluid may beadmitted into the lower end of the cylinder 18 through port extending.centrally through the cylinder cover plate 19 and the retaining screw23. With the piston 24 in its upper position the upper bevelled end 27of the piston 24 is adapted to contact with a tapered seat 28 on thecylinder 18. These coacting surfaces 27 and 28 are carefully ground orotherwise finished so that when in contact they are in fluid tightrelation and fluid is prevented from leaking past the cylinder 18 andinto the intake passages'14. In this position of the piston 24 the'fingers 26 are held upward in contact with the valve plate 12 under thefull pressure of the compressed fluid supplied through the screw 23 asfrom a pilot valve (not shown) associated with the compressor receiver.Upon releasing or exhausting fluid from within the cylinder 18 thepiston member' 25 is forced diwnward by means of a coiled spring 29interposed between the valve seat 10 and piston member 25.

When the piston member 25 is in its lower position, which position itassumes during the normal operation of the compressor, it is desirablethat fluid be prevented from escaping from the intake passages 14 pastthe cylinder 18 and through the conduit through the screw 23. For thispurpose the upper end surface 30 of the cylinder. 18 is carefully Withinthe ground or otherwise finished so that it may e in pressure tightcontact with an annular surface 31 on the piston member 25. When thepassages 14 are at a pressure above atmospheric as when the cylinder 18forms an intermediate or high pressure cylinder of a compound compressorfluid will be prevented from escaping during the normal operation of thecompressor.

I claim:

1. In a compressor valve lifting device, a cylinder havin at one endintegral seats disposed opposite y to one another, a detachable eadclosing the outer end of said cylinder, an actuating piston comprisingtwo relatively movable piston members movable within said cylinder andformed by two telescopin members, a surface on each member adapted tocontact in fluid tight relation consecutively with its own seat on saidcylinder when the piston passes from one end of its movement to theother within the c linder.

2. In a compressor va ve lifting device, a cylinder having seats formedthereon, and an actuating piston movable within said cylinder, saidpiston comprising two parts, each part having a surface adapted tocontact in pressure tight relation consecutively1 with its own seat onsaid cylinder when t e piston passes from one end of its movement to theother within the cylinder.

3. In a compressor valve lifting device, a cylinder having seats formedthereon, an actuatin piston movable within said cylinder, said p stoncomprising two parts, each part havin a surface adapted to contact inpressure tight relation consecutively with its own seat on said cylinderwhen the piston passes from one end of its movement to the other withinthe cylinder, and fluid pressure means to move both parts of saidactuating piston simultaneously in the same direction within said(iylinder.

4. n a compressor valve lifting device, a cylinder having opposed seatsformed thereon adjacent one end and an actuatin piston movable withinsaid cylinder, saitf piston comprising two parts, eachpart having asurface adapted to contact in pressure tight relation consecutively withits own seat on said cylinder when the piston passes from one end of itsmovement to the other within elation consecutively with its own seat onsaid cylinder when the piston passes from one end of its movement to theother. within the cylinder.

6. In a compressor valve lifting device, a cylinder having opposedintegral seats oppositely disposed thereon, an actuating piston for saiddevice movable within said cylinder and. comprising two piston membersone within the other and slidable relative to each other, a surface oneach piston member adapted to contact in fluid tight relationconsecutively with its own seat on said cylinder when the piston passesfrom one end of its movement to the other within the cylinder, and fluidpressure'means to simultaneously move said piston members in the samedirection to engage a surface on one piston memv a her with itss'eat.

7. In a compressor valve llftlng device, a

movement of said actuating piston in the direction to effect lifting ofa valve.

in testimony whereof, I hereto afiix my signature.

WILLIAM C. MERWARTH.

